Although obesity is one of the outstanding health problems in the United States, little is known about the factors which lead to its development at the cellular level. The aims of this research are to delineate some of the enzymatic profiles of adipose tissue during its normal growth and development and during the development of obesity. Data from normal animals will be compared to that from animals with genetic obesity and early overnutrition. The activity of thymidine kinase and its variants, lipoprotein lipase and hormone sensitive lipase will be measured. The nature of some of the differences noted between lean and obese animals will be investigated. The results will be correlated with changes in fat cell number and size. The data will be analyzed with the objective being to understand the cellular mechanisms which lead to obesity and to develop an enzymatic profile which could be used to detect the onset of a hypercelluar or hypertrophic state in biopsy samples from an at-risk human population.